Thursday, 5 January 2012

Tim Tyler: Mesoudi, Cultural evolution (review)

Hi, I'm Tim Tyler, and this is a review of this book: Cultural evolution by Alex Mesoudi.

This is a great book about the important topic of cultural evolution.

Alex Mesoudi is an experimental psychologist working in the field, and has previously published numerous papers and a PhD thesis on the topic.

His book lays out the case for a Darwinian theory of cultural evolution in plain language, in a manner which should be comprehensible to a wide audience.

The preface states his aim with the book - which he says "is to nudge the social sciences along a little". He does this by illustrating the progress that has been made in explaining culture scientifically using Darwinian evolutionary theory.

The book is divided up into introductory material, microevolution, macroevolution, experimental work, field work, evolutionary economics, culture in non-human animals and a chapter about the coming evolutionary synthesis for the social sciences.

The writing is dense, clear and polished. The first three chapters are great - so best to start at the beginning. Much of the second half of the book consists of summarising literature in the field, which Mesoudi does pretty well.

The book does a good job of making its case. Most readers will probably come away convinced that the vast majority of Mesoudi's ideas on the topic are correct.

The book has several themes. One is that cultural evolution is Darwinian. Another is that cultural evolution is not neoDarwinian. That is true, but it probably goes for organic evolution as well.

Mesoudi proposes that we need a Darwinian synthesis for the social sciences - mirroring the neoDarwinian synthesis that took place in the natural sciences in the 1930s and the 1940s. That is true - we do need something a lot like that.

At this stage, it is time for some objections:

The neoDarwinian synthesis that took place in the natural sciences left out symbiosis. The cultural Darwinian synthesis that Mesoudi proposes also apparently leaves out symbiosis. Mesoudi's whole book has no mention of mutualism, parasitism, epidemiology or immunology in a cultural context. This is surely a big mistake. Cultural evolution is dominated by the phenomenon of symbiosis. The models on which modern strains of cultural evolution are based were originally drawn from epidemiology. Mirroring the sutuation in the 1940s, we do have a pioneering theory of cultural symbiosis - due partly to Cloak (1975) which was popularised by Dawkins (1976). However, Mesoudi dismisses this work as being a "fad". Back in the 1940s the neoDarwinian synthesis had an excuse for leaving out symbiosis - because it was very poorly understood at that stage. Now, symbiosis is still poorly understood, but we know at least enough about it to know that we can't leave it out.

On a possibly-related point, Mesoudi's account of culture is incredibly positive. Mesoudi gives an argument for culture being adaptive, and barely mentions any other possibility. After a while I was on the lookout for any mentions at all of cultural traits that were deleterious to their hosts. In the whole book, I found: celibate priests, the small family size norm and suicide bombers. So: some deleterious cultural traits are mentioned - but that is an astoundingly-short list for a 264-page book on this topic. Perhaps Mesoudi's lack of treatment of cultural parasitology and immunology arises partly from an under-appreciation of the significance of deleterious cultural traits. As the obesity and smoking epidemics illustrate, deleterious cultural traits are actually commonplace. Culture is not always there to help its hosts - sometimes it acts to manipulate and sabotage them for the benefit of others. Addictions caused by drugs, pornography and chocolate gaueau typically don't benefit their hosts, but rather benefit the C.E.O.s of companies that push those sorts of product. Organisms need a cultural immune system to help them to weed out these harmful cultural traits. From my perspective, missing out so much of the negative side of culture results in an unbalanced and incomplete treatment.

While Mesoudi's call for a Darwinian synthesis for the social sciences is to be endorsed, the social sciences have repelled biologically-inspired invasions before on multiple occsations. They are well adapted to an ecosystem consisting of regular attempted raids from biologically-inspired theorists. One of the contributors to these failures was that the biology was wrong. While obviously, too much further delay would be undesirable, we should try to make the science as good as we reasonably can this time - or at least give it our best shot. A crippled symbiosis-free version of Darwinism would only bring the social sciences up to the biology of the 1940s. We should be able to manage better than that.

Another complaint is that Mesoudi slams the concept of evolutionary progress - pointing to unilinear progress theories that inspired social Darwinism and claiming the evolution is a ladder - not a bush. However, progress in organic and cultural evolution is just too obvious to deny. Attempts to deny it appear to stem mainly from the notion of political correctness. The idea has been promoted in modern times by the Marxism-inspired theorist Steven J. Gould. I think the political subtext in this case similar to the one in Gould's farcical book about intelligence testing: to promote equality, by making sure that all people and societies are equally evolved. Instead of such nonsense, evolution is better viewed as a giant optimisation process, set up to maximise entropy. As such it is incredibly directional. It is very strange to hear people denying evolutionary progress in modern times, when it is staring us so clearly in the face. I think scientists should unite in pointing out what nonsense progress denialism really is.

Though promoting the role of evolutionary theory, Mesoudi doesn't really go into the game theory, chaos theory, cybernetics, maths - and the recap on the basics of the scientific method - that would also be needed to unite the social sciences. However, given his focus in this book, that seems to be excusable.

A few less-significant criticisms:

Mesoudi dismisses Campbell's Blind Variation with Selective Retention (BVSR) thesis as being neoDarwinian - for insisting on blind variation. However, this criticism appears to be based on a popular misunderstanding of Campbell's idea. Contrary to what the name might suggest, Campbell did not claim that evolutionary variation was "blind". His claim was more like: either variation is blind or it is based on knowledge previously obtained, in which case there should still be some element of blind variation involved. That idea is quite compatible with many kinds of directed variation - so the existence of such variation does not contradict Campbell's idea. I'm not claiming that Campbell was right here - just that variation that is biased towards being adaptive is perfectly consistent with his idea.

Mesoudi discusses the controversy over whether cultural inheritance is Lamarckian. He cites those that claim that it is not - but doesn't really explain their argument - so a reader unfamilar with this topic can't easily make out the details of the case that Mesoudi is arguing against. A common criticism of the claim that cultural inheritance is Lamarckian is that similar arguments usually also classify dogs passing on "acquired" fleas to their offspring as being "Lamarckian inheritance" - which is contrary to common usage of the term "Lamarckian inheritance" in biology. Mesoudi's examples of innovation appear to be vulnerable to this objection - and it is a pretty fatal one - so these examples seem to be wasted.

Mesoudi - correctly - says that Lamarckian inheritance depends on the genotype/phenotype split. Then he then gives an "internalist" statement of that split - which places the cultural genotype in human brains and the cultural phenotype in behaviour and artifacts. Externalists probably won't find an argument based on these premises very convincing. What would be more convincing is the existence of a non-trivial developmental process. For example, if a cake was being baked, there would be no doubt about where to put the phenotype/genotype split. However, Mesoudi doesn't give such an example - leaving the location of the cultural phenotype merely assumed - and so failing to make much of a case for Lamarckian inheritance. I don't disagree with Mesoudi's conclusion - but I think that his supporting argument would only convince other internalists - which doesn't seem to be worth very much.

A few other differences and criticsms:

Mesoudi apparently thinks that non-cumulative cultural change does not qualify as being a form of Darwinian evolution - while, surely, it does.

Mesoudi offers a rather sympathetic treatment to cultural group selection - whereas I am more critical. For example, Mesoudi offers competition between firms as a modern example. However employees move between firms constantly, carrying genes and culture with them. It is true that there are non-disclosure agreements - but their effect is limited. When firms go bankrupt, their employees do not die, and much of the corporate culture is carried away by them - or else sold as "intellectual property" assets. With this much flow of genes and culture going on between organisations, it would be very difficult to make any kind of group selection model operate successfully.

Towards the end of the book Mesoudi attempts to explain why humans have cumulative culture while other animals do not. Accepting this premise for the sake of argument, Mesoudi gives a rather inconclusive analysis that manages to miss out a number of what I consider to be the main candidates.

To summarise, this is a great book on an important topic. It is a book which I was waiting to read all year. I do think there are some rather glaring omissions, though - as well as some rather uneven coverage of the field's topics. I enjoyed the literature summary - though perhaps a general reader might get a little bogged down by all the details. It's great that we have Mesoudi working in this field. It badly needs outstanding communicators to help get its message across to the rest of the world.